Tohickon Creek, Bucks Co. to be stocked for opening day, 2009

[Mike]

Tohickon Creek, Bucks Co. has been added to the preseason stocking program for 2009. For the previous 26 year or so it has been stocked only during the inseason stocking period. Anglers have generally behaved themselves knowing the landowner sensitivities to this particular stocking program and most landowners are now willing to allow preseason stocking to occur. Public riparian lands include Ralph Stover State Park, Bucks Co's Tohickon Valley Park, and an additional county park property. Much of the stocked trout stretch is in a beatiful location and the portion in the gorge, which is float stocked, would remind one of north central Pa. This fairly wide, tumbling, and scenic stream is excellent early season fly fishing before the stream warms in May. The stream will be stocked following the annual weekend white-water kayaking and canoeing release from Nockamixon Lake.

 

[LouM]

After the season opens ACE will then cut back the flow as it always does to about 13cfm and there goes the fishing. The Tohickon could be a tail water fishery if they didn't hold back the water for the kayakers. ACE strikes again!

 

[Mike]

Nockamixon dam is operated by DCNR, not by the ACOE. The 13 cfs that you mention is approximately DCNR's required conservation release. When they are at the point that the release flow is that low, then any additional volume in release would begin to drain the lake, which affects boat ramp usage as well as lake fish habitat. The lakes's drainage basin geology does not yield a high volume of water. A tail-water coldwater fishery would require a considerable drawdown of the lake and would greatly impact recreation there. The lake is the centerpiece of Nockamixon State Park and, frankly, I sincerely doubt that usage in the theoretical tailwater fishery would make up for lost usage in park if the lake were being drained.

 

[tabasco_joe]

Thanks for the info Mike. Does the PFBC hold any influence with the Corp on Lake Nockamixon to help out with flow rates? As Lou says the stream has a lot more potential than we currently experience.

Looks like Mike and I were typing at the same time and he answered my question.

 

[LehighRegular]

Mike

Can you clarify your statement here, I think it may be a bit misleading:

A tail-water coldwater fishery would require a considerable drawdown of the lake and would greatly impact recreation there

I don't know much about the fishery or potential for a tailwater coldwater fishery. One would have to take a closer look at the potential. Here are few questions as food for thought:
1) How is the water released from the lake (i.e. bottom releases, multi-level ports/selective withdrawal, spillway, etc).
2) How much coldwater is actually available in the lake?
3) Is there enough coldwater in the lake and can it be sustained to maintain a coldwater release?

I wouldn't worry about volume immediately but first look if this is even possible.

Mike - it appears based on your post that it is impossible to have a coldwater release from the lake or it will jeopardize the lake fishery and recreation. Can both be accomplished? It does happen other places in this country. Has the PFBC even looked into this potential??? Or are you/PFBC just writing it off?

Why is drawdown of the lake necessary?

I think there appears to be some interest in this by the angling public and may need futher explaination on your part.

DCNR and the PFBC work very closely together so I would think any agreement would be easily accomplished.

 

[LouM]

When water is released from the dam the creek is severly damaged, as far as erosion goes,you only have to look at the banks to see the damage. If the water was not released all at once but over a period of time it would reduce the erosion problem and extend the amount of time that it could be fished. The present system has also had an adverse effect on the smallmouth,population and on migratry species such as shad and carp that come up from the Delaware.

 

[tabasco_joe]

Mike, if there was sufficient water in the lake what flow would be required for the Tohicken to be a viable tailwater? Another question; I believe most of the land between Nockamixon park boundary and Ralph Stover is private. How much access is there along the stream?

 

[LehighRegular]

That would depend on how many miles you want to have a coldwater fishery and how far down stream you want to have water temps below 68 F. A quetion I don't think Mike can even guess at right now.

First priority is to have the water cold

 

[tabasco_joe]

LehighRegular wrote:
That would depend on how many miles you want to have a coldwater fishery and how far down stream you want to have water temps below 68 F. A question I don't think Mike can even guess at right now.

First priority is to have the water cold

My understanding from talking with a park officer years ago was that it had bottom release capability. The lake is deep and narrow so what Mike says makes sense. It wouldn't be too hard to calculate the impact of a given draw down.

I'm more interested in a guess on flow rate based on the stream bed size.

 

[JackM]

LehighRegular wrote:
First priority is to have the water cold

Whose first priority? That is the question. Unless I am missing something, Mike is saying between the whitewater release and the recreational value of the lake, there is no way to also sustain a tailrace coldwater fishery.

 

[LehighRegular]

To have a coldwater tailwater fishery...the water must be cold, first a foremost

Because there are whitewater releases and the "recreational value" of the lake is NO reason not to have a coldwater tailwater fishery. Both can be accomplished and still maintain the recreational value of the lake and have WW releases.

I don't understand how the recreational value of the lake would be jeopardized by creating a coldwater tailwater fishery? THis needs further explaination by Mike. He did discuss something about the need to drawdown of the lake, but why is drawdown required? Mike mentioned that any additional volume over 13cfs would draw the lake down and comprimise boat launches, etc. But why is there a need to draw down the lake?

Why not just match inflow with out flow as long as the release is cold? Can that be accomplished?

How far down stream can trout favorable temps be maintained at conservation release of 13cfs? Half mile, 1 mile, 2 miles???

The only restriction would be or could be, is if there is not a sufficient coldwater pool in the lake to maintain the tailwater fishery.

The others "issues" mentioned in this thread sound like a lame excuse not to look into or do something to benefit this states trout fisheries and provide more trout angling oppurtunities in a region were they would probably be highly welcomed.

 

[JackM]

I think what Mike said was IF releases are made above about 13 cfs it would RESULT in drawdown. In other words, the lake inflow volume is about equivalent to a 13 cfs release from the dam so that any additional volume of release would result in more water leaving the impoundment than is flowing into it THUS resulting in a lowering of the lake levels (i.e, "drawdown"). As I said, it is possible I am missing something, but this is how I understand the issue presented.

 

[LehighRegular]

OK...but why is lowering the lake necessary?

 

[tabasco_joe]

JackM wrote:
I think what Mike said was IF releases are made above about 13 cfs it would RESULT in drawdown. In other words, the lake inflow volume is about equivalent to a 13 cfs release from the dam so that any additional volume of release would result in more water leaving the impoundment than is flowing into it THUS resulting in a lowering of the lake levels (i.e, "drawdown"). As I said, it is possible I am missing something, but this is how I understand the issue presented.

That's my take on Mike's comment. What I would like to know is how much of a drawdown would happen if say 25 CFS were released. It would take some statistical analysis on average rainfall, etc.

In my bass fishing days there were years I had my boat on that water close to 60 days. The lake does rise a foot or two during large periods of rain. The ramps aren't usable with much of a drawdown, maybe two feet.

Part of the issue comes from a lack of trust built up with various entities that run the lakes. In eastern Pa this includes the lakes feeding the Delaware and the Lehigh rivers. With a history of unfavorable management for those fisheries we tend to second guess all release plans. All large lakes should have well engineered, publicly available release plans. This would go a long way towards building that trust and facilitate public discussion on how to manage the resource.

 

[JackM]

LehighRegular wrote:
OK...but why is lowering the lake necessary?

I have to think we are talking past one another somehow. The lowering would be a result of releases greater than 13 cfs when the inflow conditions are dry. In other words, it is a necessary result, not a necessity in the sense that it must be done. In order to maintain reasonable lake levels, the outflow has to be restricted to 13 cfs unless there is a particularly wet period that allows greater release volume while maintaining a stable lake level. I can't think of any other way to explain what I think Mike is saying.

 

[Will]

I agree with Jack about what Mike seems to be saying. I had a different question. Would eliminating the annual whitewater release "save" enough wated to allow a larger sustained coldwater outflow without a drawdown? Somebody mentioned that the large concentrated release causes erosion. That is one reason to eliminate it. Another might be that a year-round coldwater fishery might provide more person-hours of recreational opportunities and more revenue to the local economy than a once-per-year whitewater weekend. On the other hand, the kaykers might reasonably feel that one weekend per year is not too much to ask.

Second question - what about the temp of the existing release. 13cfs isn't a lot, but if its all cold water bottom release, I'd expect that some trout could hold over during the hot months by crowding the outflow (as they do with small tribs in larger rivers). So if that is not happening, one step that might help the trout without hurting any non-angler user group would be to make the minimum release all bottom-release. Of course, maybe I am off base and that is being done already.

 

[LehighRegular]

Jack

OK...then don't release water greater than inflow to cause drawdown. All that would need to be done is to keep the release cold.

Didn't Mike's post indicated that draw down was required to create a coldwater tailwater fishery?...or at least that is how I interpreted his post.

Will... I think the Kayakers have releases twice per year, usually during cold or cool weather months (March & October). I don't believe the releases would deplete the coldwater pool significantly.

 

[JackM]

Yes, I think that there is some belief that 13 cfs release of the coldest water possible would be insufficient to create a cold-water fishery. I don't know what 13 cfs looks like, but if it results in a shallow creek, then mid-summer, that water won't remain cold for very long.

 

[LehighRegular]

how far down stream would be the question, which I dont think is known. Gradient plays a big role in how far down stream those trout favorable temps can be sustained and stream structure & width too. Ambient air temps are limiting during the hot months. I don't know enough about the stream to make a judgement.

13 cfs on Valley creek is low, is Tohickon about the same size/width as Valley? I assume a little bigger. How does 13 cfs look like? Could trout survive if temps were cold enough?

http://waterdata.usgs.gov/pa/nwis/uv?cb_00065=on&cb_00060=on&format=gif_default&period=60&site_no=01459500

Well, if you can maintain temps in the first mile, is that worth it?

 

[jayL]

It's a pretty valuable warm water/smallmouth fishery too, from what I hear. I'd be curious to see what the effects of this would be on them, as I think it would be best to displace as few smallies as possible. I don't think it would pose that much of a problem, personally, if the temps would be kept at a level similar to the tully.

If a coldwater/smallmouth fishery were to be made, I'd probably hit it a few times a year...